VISUAL PROCESSING IMPAIRMENT AND RISK OF MOTOR-VEHICLE CRASH AMONG OLDER ADULTS

Context.-Motor vehicle crash risk in older drivers has been associated with visual acuity loss, but only weakly so, suggesting other factors contribute. The useful field of view is a measure that reflects decli ne in visual sensory function, slowed visual processing speed, and imp aired visual attention skills. Objective.-To identify whether measures of visual processing ability, including the useful field of view test , are associated with crash involvement by older drivers. Design.-Pros pective cohort study with 3 years of follow-up, 1990-1993. Setting.-Op hthalmology clinic assessment of community-based sample. Patients.-A t otal of 294 drivers aged 55 to 87 years at enrollment. Main Outcome Me asure.-Motor vehicle crash occurrence. Results.-Older drivers with a 4 0% or greater impairment in the useful field of view were 2.2 times (9 5% confidence interval, 1.2-4.1) more likely to incur a crash during 3 years of follow-up, after adjusting for age, sex, race, chronic medic al conditions, mental status, and days driven per week, This associati on was primarily mediated by difficulty in dividing attention under br ief target durations. Conclusion.-Reduction in the useful field of vie w increases crash risk in older drivers, Given the relatively high pre valence of visual processing impairment among the elderly, visual dysf unction and eye disease deserve further examination as causes of motor vehicle crashes and injury.